Three-shoe brake



- S p 10, 1929. A. TAUB El AL 1,727,797

THREE SHOE BRAKE Filed June 2'7, 1927' 3 Sheets-Sheet l THREE SHOE BRAKE a mat/"2a a 6-7, 2124/ P 10, 1929- R TAuB ET AL 7,

THREE sHoE BRAKE Filed June 27, 192"? 5 Sheets-Sheet 5 I ZNLNN? Wag-i Patented Sept. 10, 1929.

v UNITED STATES PA EN OFFICE.

ALEX TAUB AND EINAR WALLER, F DETROIT, MICHIGAN, ASSIGNORS TO GENERAL MOTORS CORPORATION, OF DETROIT, MICHIGAN, A CORPORATION OF DELAWARE.

THREE-SHOE BRAKE.

Application filed June 27,

This invention relates to brakes and has been designed more particularly as an improved brake for motor vehicles.

An object of the invention is to provide an internal rigid shoe brake having a servo action. As a further object the invention aims to utilize the self-actuation of one shoe me chanically applied to actuate a second shoe through the aid of a swinging link carrying the pin by which said shoes are pivoted.together. Furthermore, the invention is similarly operative, both in a forward and in a rearward direction of movement. Other objects and advantages will be understood from the following specification which is to be read in connection with the accompanying draw- 1ng.

In the drawing:

Figure 1 is a vertical section through a brake embodying our invention, the figure being in section substantially on the line 11 of.

Figure 2.

Figure 2 is a transverse vertical section on line 22 of Figure 1.

Figure 3 is a view looking in the direction of the arrows on line 3-3 of Figure 1, parts broken away.

Figure 4 is a view looking in the direction of the arrows on line 44 of Figure 1, parts broken away and in section.

Figure 5 is a View corresponding to Figure 1 but illustrating a modified form. The section shown by this figure is on line 55 of Figure 6.

Figure 6 is a transverse vertical section of this modified form.

Figure 7 is a view looking in the direction of the arrows on line 7-7 of Figure 5.

Figure 8 is a View looking in the direction of the arrows on line 88 of Figure 5.

Figure 9 is another modified form, the figure being a section corresponding to Figure 1 and indicated by line 9-9 of Figure 10.

Figure 10 is a transverse section of the invention shown in Figure 9.

Figure 11 is a view looking in the direction of the arrows on line 11-'-11 of Figure 9.

Figure 12 is a view looking in the direction of the arrows on line 12-12 of Figure 9.

Referring first to Figures 1 to 4, inclusive,

1927. Serial No. 201,720.

numeral 15 represents a brake drum having an annular shoe engaging ortion 17 This drum is shown as 'astened to a wheel 19 by fastening means 21. It will be understood that this attachment of the drum to a rotating wheel is illustrative only. The drum may becarried by an rotating part, the motion of which is to e stopped. The outer edge of the ring portion 17 may be turned outwardly as' at 23 to the better protect the brake, keeping out water and dirt.

The hollow brake drumlis closed b a fixed plate 25. This plate may be secured by fastening means 27 to any convenient non-rotating part, as for example to the fixed axle 29. For the purpose of excluding dust and wa ter there may be secured to the outer peripheral portion of fixed plate 25 a substantially U-shaped uard 31.

The bra e may be otherwise operated but we have shown and prefer to operate it by means of a cam. For "mounting the cam the arrangement best shown in Figure 3 may be used. A plate 33 engages the inner face of the fixed plate 25 and is secured thereto by bolts 35 with nuts 37. This plate has a circular sleeve portion 39 extending through the fixed plate 25, the sleeve portion being intended to receive the shaft 41 carrying the cam 43. The bolts 35 are provided with enlargements 45 and engaging the enlargements 45 of the bolts is an inner plate 47 the latter plate being held in position by nuts 49. Two operating shoes 51 and 53 are formed with radial ribs 55. The are shaped faces 57 of the shoes are provided with linings 59, these linings being intended to provide frictional engagement with the inner surfaceof the drum. Atthe adjacent ends of the shoes the portions 55 and 57 terminate in fiat faces 61 which are engaged by the cam. The ribs or webs 55 are provided with openings 63 to accommodate the bolts 35. Somewhat removed from the cam engaging portion of the two shoes 51 and 53 are openings 65 to receive the ends of a releasing spring 67, this spring serving to normally pull the shoes away from the drum and against the cam. A third shoe 69 similarly constructed is located between the ends of shoes 53 and 55. The web portions of the 100 end of shoe 69 then becoming the anchor.

shoes 55 and 69 are pivoted together by means of a pivot pin 71 within the drum. A similar pivot pin 71 unites the adjacent ends of shoes 53 and 69. Pivoted by means of pins 73 in the fixed plate are links 75. These links 75 extend away from each other and are connected to the pins 71 w ich pivotally connect the ad-- jacent ends of the brake shoes as already explained. Openings 65 are also provided in brake shoe 69 and coil springs 67 are con nected to the shoe 69 at the openings 65 and are also connected to suitable fastening means 77 carried by selected securing bolts 27 used for attaching the fixed plate 25. These springs serve, together with spring 67, to release the several shocs from the drum when the braking action is withdrawn. For limiting the inward movement of the shoes away from the drum a suitable stop should be pro vided. In Figures 1 and 4: we have shown an eccentric 7 9 pivoted by means of a bolt 81, one such eccentric being located adjacent each pivot pin 71. By suitably adjusting the eccentric the extent of release action under the influence of the springs may be predetermined.

The operation of the brake will be readily understood and maybe briefly stated as follows. Let it be assumed that the forward direction of travel of the vehicle is represented by arrow A, Figure 1. When the cam shaft 41 is rotated by the brake pedal or lever the shoes 51 and 53 are thrust outwardly toward the drum. In the direction of travel indicated, the rotary effect of the drum tends to release shoe 53 from the drum, and tends to cause self-actuation of shoe 55'. This has the effect of tending to carry the shoe 55 around with the drum and because of its connection at 71 the shoe 69 would also have the same movement. However, the connection of shoe 69 through the link 75 with pivot 73 gives the further end of shoe 69 substantially a fixed anchor. The effect of self-actuation of shoe 55 is, therefore, to cause the link 75 (connect-- ing the pivot 7 3 with the pin 71 uniting the adjacent ends of shoes 55 and 69) to swing in a counter-clockwise direction about its pivot 7 3. This movement may be resolved into two components, one of which will be radial to the drum. The actuation of the cam therefore upon the shoe 55 is supplemented by the action of shoe 69. In a similar way should the vehicle be travelling in a reverse direction the shoe 53 becomes self-actuating and through its connection with shoe 69 ape plies the latter to the drum, the furthermoit t should be observed that shoe 53 is shorter than shoe 55, this provision being made for. the reason that the intensity of braking when the vehicle is traveling in reverse may well be less. 1

There has thus been provided a brake which is comparatively easy to operate owing to its servo action, and which operates on the same principle whether driving forward or in reverse.

I11 Figures 5, 6, and 8 the form of invention is quite similar to that already described. In this form instead of the shoes 51, 53 and 69 there are employed shoes 51, 53 and 69. These shoes are formed by stamping and are of U-shape as perhaps best shown in Figure 6. \Vithin the arms 81 of the U-shaped shoes adjaceht the cam there are secured by rivets or the like 83 terminal cam engaging plates 85. At the opposite ends of shoes 51 and 53 and at both ends of shoe 69 are secured by. rivets 85, plates 87 which have apertured hinge pin engaging ends 89 to receive the pins 71. These pins are carried by links 75 pivoted to the fixed plate by pivot pins 73 as intheform already described. The springs 67 and 67 are used as before. Instead of the eccentric means to determine the extent of the release there is provided a substitute device shown in Figures 5 and 6. A plate member 91 is mounted for sliding movement ust within the fixed plate 25. A slot 93 is provided in plate 25 and through this slot passes a bolt 95, the bolt movable in the slot carrying there with the plate 91 for vertical adjustment. At the base-of plate91 is an inturned flange 97 which is adapted to engage one of the walls 81 of the U-shaped sl1oe;69-. By suitably adjusting the bolt 95 theflange 97 may be located as desired to thereby limit the release movement of the brake shoes. A somewhat simplified form of cam shaft bearing is shown. This involves simply a sleeve member 39' having a flange 33 secured by bolts to the fixed plate 25. In other respects this form of the invention corresponds with the form shown in Figures 1 to 5 inclusive. The operation is also the same and requires no further description.

The third form of invention is shown in Figures 9, 10, 11 and 12. In this form of the invention the cam shaft is mounted substantially as before described. 'The U-shaped stamped shoes are also used. The dust guard 31 has been omitted with the anticipation that dirt and water could be kept out with the use of the flared brake drum as shown at 23 together with the close fitting brake support 25. In this form we have further simplified the release limiting device. The plate 25 is formed with a slot 93 through which passes a stop member 95. This member is shown as provided with flats 99 engaging the wall of slot 93. By releasing a nut on stop 95', this stop may be adjusted vertically. This vertical adjustment in an obvious way limits the release movement in the shoe. Another feature of difference in this third formlies in the use of shoes of equal length, shoes 51' taking the place of 51' and 53 in the form shown by Figure 5. To prevent rattling we have placed a coilspring 101 on pivot bolt 71.

In other respects this form of the invention is quite similar to that already described.

e claim:

1. In abrake, a drum,-a servo shoe, a second shoe, a pivotal connection between said shoes, means connected to said shoes at said connection providing a limited body movement of said pivot.

2. The invention defined by claim 1, said movement being on an are having a component radial with reference to the brake drum.

3. In a brake, a drum, a servo shoe, means to apply the shoe to the drum, a second shoe, said shoes lying in substantially the same circumferential line, means pivotally connecting adjacent ends of said shoes, means mounting said pivotal connection whereby said connection is given bodily movement having a radial component.

4. In an internal brake, a fixed plate, a rotating drum, a servo shoe within said drum, a

second shoe circumferentiall beyond said servo shoe, means to pivot a jacent ends of said shoes together, a link pivoted to said fixed plate and carrying said pivot means. and means to anchor the remote end of said second shoe.

5. The invention defined by claim 4, said last mentioned means including a second link, said second link positioned to restrain said second shoe from circumferential movement when the first link swings on its pivot to actuate the second shoe.

6. In a brake, a drum, a plurality of shoes circumferentially arranged within said drum, pivot means connecting the ends of one of said shoes with the adjacent ends of the other shoes, links carrying said pivot means, fixed pivots for said links, said fixed pivots being located between said shoe pivots, and means to move said other shoes into frictional engagement with the drum.

7. The invention defined by claim 6, one of said other shoes being of lesser peripheral ex tent whereby the braking action in forward driving is greater than in rearward driving.

8. In a brake, a rotatable drum, a fixed plate, a plurality of pins carried by said fixed plate and extendinginto said drum, links on said pins extending away from each other, a brake shoe within said drum, the remote ends of said links pivoted to the ends of said shoe, other shoes in said drum, one end of each of said other shoes pivoted to said remote ends of the links, and brake a plying means at the adjacent ends of said ot er shoes.

In testimony whereof we aflix our signatures.

ALEX TAUB. EINAR WALLER. 

